Ocean's "dead zone" continues to expand

The Gulf of Mexico is slowly dying - and it’s all our fault. Every year, the farms that line the Mississippi river basin use enormous quantities of nitrogen-based fertilizers which run off into the Big River and are belched out into the ocean. The artificial surge in nutrients triggers huge algal blooms, and as the algae decomposes, it deoxygenates vast tracts of the ocean. The effects are devastating: Without oxygen, previously thriving ecosystems literally choke to death, and the seabed becomes a desert.

The problem is already taking a toll on coastal economies, with shrimp catches in Texas and Louisiana slumping as the marine “dead zone” spreads. And this year, the problem looks set to be worse than ever: Researchers say the offshore dead zone is likely to expand to a record-breaking 8,800 square miles - an area the size of New Jersey.

The spread of the dead zone is partly due to widespread flooding, possibly caused by global warming, which this year brought especially large quantities of chemical waste into the Mississippi. The single biggest culprit, though, is the American infatuation with corn ethanol: Farmers are planting more corn per acre than ever before in a bid to cash in on federal biofuel mandates. That’s rapidly depleting the soil along the banks of the Mississippi, leading to a massive new demand for the chemical fertilizers responsible for deoxygenation.

Researchers say that we’re rapidly approaching the point of no return. If the dead zone continues to spread, shrimp and other seabed dwellers could be left with nowhere to run and find themselves literally pushed off the continental shelf. If that happens, the Gulf’s valuable crustaceans could be permanently replaced by an expanse of worthless - and possibly carcinogenic - bacterial sludge.

To avert that disaster, the Environmental Protection Agency’s (EPA) scientists say we need a swift 40 percent cut in fertilizer pollution along the banks of the Mississippi. Unfortunately, the EPA’s policy-setting task force has shown no inclination to act on that recommendation. In a report published last month, the task force set no specific goals or deadlines, and made only a vague suggestion that the states involved should try to sort things out before the task force reconvenes in 2013.

That’s a cop-out, of course: Without federal leadership, upstream farm states have little incentive to cut their fertilizer use. With lawmakers in Washington still swooning over corn ethanol and the EPA apparently content to pass the buck, the future looks pretty bleak both for the Gulf’s ecosystems and for the coastal communities who depend upon them.